Laser cutting method and laser cutter

Abstract

A development of a laser cutting method and a laser cutter in which the adverse effects such as self burning to the cutting surface can be prevented, when the material is cut at a high speed, has been desired. In order to achieve the object, the present invention provides a laser cutting method and a laser cutter in which a cutting laser beam 22 is applied to a material 25 to be cut at a cutting point 26, while ejecting gases 23 and 24 to the cutting point 26 or its surrounding area from a plurality of nozzle openings 30 and 31 arranged in a ring or in a line, wherein the oxygen concentrations of the gases 23 and 24 ejecting from at least one of the nozzle opening 30 and 31 are changed to adjust the oxygen concentration distribution in an area within several millimeters of the cutting point 26; thereby the cutting quality can be improved.

Description

The present invention relates to a laser cutting method and a laser cutter.When mild steel is cut with a laser having a small power relative to the thickness of the mild steel, sufficient cutting laser energy can be obtained at the vicinity of the surface of the mild steel at which the laser is applied. However, there are many cases in which sufficient cutting laser energy cannot arrive at the inside of the mild steel. Therefore, in recent years, high concentration (purity) oxygen (having a concentration (purity) of 99.5% or more) is supplied to the vicinity of the cutting point by use a co-axial double nozzle 1a and 1b as shown in FIGS. 10 and 11, a co-axial triple nozzle (not shown in Figures), or an auxiliary nozzle 2 as shown in FIG. 12. Thereby, a sufficient oxygen concentration for cutting the inside of the mild steel is maintained. Heat is generated due to the oxidation reaction between steel and the supplied oxygen, and the heat compensates for the deficiency of laser energy...

AI Technical Summary

Benefits of technology

FIG. 4 shows the effects obtained from the first preferred embodiment of the laser cutting method according to the present invention, and shows the roughness of the cutting surface with respect to the distance from the top surface when mild steel having a thickness of 12 mm is cut.

FIG. 5 shows the effects obtained from the first embodiment of the laser cutting method according to the present invention, and shows the roughness of the cutting surface with respect to the distance from the top surface when mild steel having a thickness of 22 mm is cut.

Problems solved by technology

However, there are many cases in which sufficient cutting laser energy cannot arrive at the inside of the mild steel.

Therefore, it is difficult to maintain a suitable cutting quality when the thickness or the kinds of the material to be cut is changed.

An excess combustion heat is generated due to the small change in conditions when the material is cut, and easily adversely effects to a quality of the cut surface.

Then excess combustion energy adversely effects to the cutting surface and the cutting quality.

Consequently, for example, as shown in FIG. 15, a normal cutting quality can be obtained at the vicinity of the surface 4 of the material to be cut; however, an abnormal cutting quality is often obtained on the inside of the material to be cut.

Therefore, it is impossible to sufficiently improve the cutting quality.

Therefore, it is impossible to solve the problem.

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